Heated wiper blade for motor vehicles and the like

ABSTRACT

A heated wiper blade for motor vehicles includes an elongated flexible beam and a heating element extending along the beam. The heating element may be configured to provide increased heat at the central portion of the blade and at the opposite ends of the blade. The heating element is comprised of an electrical conductor material that varies the amperage drawn between hot and cold ambient temperature operation. The flexible beam may include curved end portions and a flat or reduced curvature central portion. The heating element is preferably covered and sealed off to prevent loss of heat energy.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM TO PRIORITY

This application is a continuation-in-part of and claims priority under 35 U.S.C. §120 to commonly owned, co-pending, related U.S. patent application Ser. No. 13/177,382, filed Jul. 6, 2011, entitled HEATED WIPER BLADE FOR MOTOR VEHICLES AND LIKE, which claimed priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/361,628, filed Jul. 6, 2010, the entire disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to windshield wiper blades for motor vehicles and the like, and in particular to an improved heated wiper blade and associated method.

Heated windshield wipers are generally known in the art, and include many different forms and designs. Some such heated wiper blades heat the wiper frame, arm, and blade, or a combination of these members, using a heating element or some other type of added assembly. While such wiper blades are somewhat effective, they are inconvenient to both the manufacturer and the end user. For example, they are either very costly to manufacture, thereby resulting in a high cost product that is passed through to the consumer, or they are very complex to install, thereby eliminating many of the do-it-yourself consumers. Also, such prior designs fail to consider that the wiper should work effectively with the windshield defrosting system of the motor vehicle as a fully integrated functional unit. Without the windshield defroster system, the windshield will freeze up with the accumulated snow and ice, creating a hazardous situation.

A unique frameless heated wiper assembly is disclosed in U.S. Pat. No. 7,721,382, the entire contents of which are incorporated by reference. While such wiper assemblies are generally effective, certain improvements to the same would be advantageous.

SUMMARY OF THE INVENTION

One aspect of the present invention is a heated wiper blade for motor vehicles and the like having certain improvements to the invention disclosed in U.S. Pat. No. 7,721,382, as disclosed in greater detail hereinafter.

Yet another aspect of the present invention is to provide an improved heated wiper blade and associated method that is economical to manufacture, efficient in use, and particularly well adapted for the proposed use.

These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a heating element of a heated wiper blade according to one aspect of the present invention;

FIG. 2 is a schematic view of a heated wiper blade made of conducting material;

FIG. 2A is a partially schematic view of a beam and heating element according to another aspect of the present invention;

FIG. 2B is a partially schematic view of a beam and heating element according to another aspect of the present invention;

FIG. 2C is a partially schematic view of a beam and heating element according to another aspect of the present invention;

FIG. 3 is a partially fragmentary isometric view of a portion of a motor vehicle including a heated wiper blade assembly and system according to the present invention;

FIG. 4 is a partially fragmentary, exploded isometric view of a heated wiper blade according to one aspect of the present invention;

FIG. 5 is a partially fragmentary side elevational view of the heated wiper assembly of FIG. 4;

FIG. 6 is a cross-sectional of the heated wiper blade of FIG. 5 taken along the line 6-6;

FIG. 7 is a cross-sectional view of the heated wiper blade according to another aspect of the present invention;

FIG. 8 is an exploded view of the heated wiper blade of FIG. 7;

FIG. 9 is a cross-sectional view of the heated wiper blade of FIG. 5 taken along the line 9-9; FIG. 5;

FIG. 10 is a cross-sectional view of another version of the heated wiper blade of FIG. 9;

FIG. 11 is a side elevational view of a beam for heated wiper assemblies, wherein the beam has a flat center portion;

FIG. 12 is a plan view of the beam of FIG. 11;

FIG. 13 is an isometric view of a temperature sensing unit;

FIG. 14 is a partially schematic view of a first wiring harness;

FIG. 15 is a partially schematic view of a second wiring harness;

FIG. 16 is a partially schematic view of a third wiring harness;

FIG. 17 is a partially fragmentary isometric view of a portion of a motor vehicle including a heated wiper blade assembly and system according to another embodiment of the present invention;

FIG. 18 is a partially fragmentary isometric view of a heated wiper blade according to of the present invention;

FIG. 19 is a partially fragmentary isometric view of a heated wiper blade according to the present invention; and

FIG. 20 is view of the circuit for the heated wiper blade according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal” and derivatives thereof shall relate to the invention as oriented in the attached drawing. However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

The reference numeral 1 generally designates a heated wiper blade embodying the present invention, which is schematically illustrated in FIG. 2. A heating element 2 is embedded in wiper blade 1 using a unique pattern to achieve an improved distribution of heat and wiping performance. More specifically, increased heat is provided in the center 3 of the wiper blade 1 to compensate for wind. Also, increased heat is provided at a section “W” (FIG. 2). Inner boundary 6 of W may be about 0.5 inches from each end 4 of the blade 1 to compensate for the metal portion of the blade 1 not being in contact with the heating element 2, and because the heating element cannot be positioned all the way to the ends of the beam. The illustrated heating element 2 has leads 5 disposed adjacent the center 3 of blade 1, which are connected with the electrical power system of the associated motor vehicle.

Heater element 2 may comprise a Kapton or silicone etched foil adhesive backed strip. Thermistor or other positive temperature coefficient (PTC) material on the foil strip facilitates regulation of the temperature of the blade 1, as discussed further below. Preferably, wiper blade 1 is grounded, so that only the positive lead must be run under the hood of the vehicle to the heating element 2. Electrical power to the wiper blade 1 is preferably provided only after the ignition switch of the vehicle has been turned on. Airflow is sealed off on each side of the center 3 of the wiper blades 1 utilizing a sealant or other suitable material to prevent cooling of the heating element 2. A temperature sensor 18 may be enclosed in metal casing, rather than being exposed to the open air. The etched foil strip shown in FIG. 2 is a convenient way to configure the heating element 2.

A graphite or graphite impregnated squeegee and/or rubber backing on the wiper blade 1 can be configured to have electrical power applied to heat the squeegee and/or backing. Using graphite would electrically heat and/or assist heat transfer to the wiper blade 1.

In beam-type wiper blades, there is a spring metal that is curved which follows the curve of the windshield. This metal can be substituted with carbon (graphite) that can be powered to produce heat for the wiper blade 1. Also, all of the metal brackets on current wiper blades can be made using graphite instead of metal. In other words, a non-metal blade can be heated by the electrical power of the motor vehicle.

Heated wire and/or etched foil heating tape can be embedded or extruded during the manufacturing process into the wiper bow, wiper blade backing, and/or squeegee. The bow may be composed of metal, plastic, fiberglass, and/or graphite. The backing and squeegee may be composed of rubber, embedded graphite, other materials, and/or other heat conducting materials.

A sensing and control module can be made for emergency vehicles of the type normally stored inside buildings and maintained at room temperature, that is, around 70° F. In applications such as this, the heated wiper blades 1 are preferably on and ready for use at all times. For example, if the air temperature is 70° F., a normal heated blade may get too hot if full power is supplied to the blade. Excessive power to the blades may cause the blades to get too hot, resulting in melting of rubber and/or plastic components. Thus, providing a module that reduces the electrical power supplied to the heating elements of the blades to ensure that the blades do not get too hot under such operating conditions is preferred for applications where the vehicle is maintained at room temperatures. The module includes a temperature sensor that senses the higher temperature of the storage area, and provides a reduced voltage to the heated wiper blade 1 at higher (e.g., 70° F.) temperatures. For example, most motor vehicle battery and charging systems deliver 14.6 volts after the motor vehicle has been started and approximately 12.6 volts when the motor vehicle is not running. However, the heated wiper blade 1 may only require 10.0 volts for proper heat at 70° F. The control module may be configured to provide 11.0 volts if the temperature is 30° F. and 13.0 volts at 0° F. Similarly, the controller may be configured to shut off all electrical power to the blades if the air temperature exceeds 80° F. or other predefined temperature. This provides a completely automatic system or mode that allows the heated wiper blades to be left on at all times. PTC material, thermistor, or thermostat, etc., can be utilized to accomplish this function as well.

Reducing electrical power at increased temperatures can also be accomplished to some extent by utilizing nickel 200 material for the heating element 2, such as those PTC materials where resistance changes with temperature. As the ambient air temperature goes down, the resistance of the heating element wire or etched foil decreases and the current increases, increasing the wattage of the heated wiper blade 1, thereby producing a higher temperature and a self regulating system, as discussed below.

FIG. 1 illustrates another way of manufacturing and connecting power to the heated wiper blades. By making some or all of the parts of the blade assembly from a conducting material, such as graphite, supplying electrical power to such parts causes them to heat. In FIG. 1, center bracket 13, beam 14, and squeegee 15 are made of a conducting material. FIG. 1 also shows schematically how these components can be connected to the power source by leads 5 such that electricity flows through the components. It will be understood that the leads 5 may comprise insulated wire that is routed along the blade to bracket 13, and further routed along a wiper arms 10 (FIG. 3).

As discussed in more detail below, a wiring harness may be used to electrically connect the heated wiper blade 1 to the electrical power source. The wiring harness can be made in various ways, including molded, different wiring devices, crimps, connectors, inline splices, twist connectors, waterproof connectors, plug-in connectors, and different wire lengths, sizes and colors. Different vehicles may need different wiring harnesses to accommodate various heated wiper blades. In some vehicles, like fire trucks, UPS trucks, bread trucks, etc., the wipers extend down from the bulkhead of the vehicle. This would require a different wiring harness with waterproof, ultraviolet-resistant wires and connectors.

All wires connected to the heated wiper blades are preferably flexible, ultraviolet-resistant (sun), oil-resistant, and capable of carrying at least five amps of current. All harnesses connected to the heated wiper blades also require a fuse.

A temperature sensor 18 may also be included with the wiring harness. The wiring harness may also include a module 17 and/or connectors that connect to the computer or processor associated with the motor vehicle, so that if the wires should fail or become disconnected, a warning light or signal would alert the driver. Also, fuse holders, inline fuses, on/off switches, etc., could be included with the harness.

With further reference to FIG. 3, the heated wiper blades 1 are mounted to the existing arms 10 of a vehicle windshield wiper system. The heating elements 2 of blades 1 are connected to wiring 22 utilizing disconnectable connectors 25. Alternatively, the leads 5 of heating element 2 may be connected directly to wires 22. A manual switch 21 may be disposed in the vehicle interior for operation by a user. Switch 21 is connected to module 17 by a wire 23, and module 17 is connected to vehicle battery 16 by wire 19 and to vehicle ground by a wire 19 a. In one embodiment, a temperature sensor 18 may be mounted directly behind a vehicle grill 28 such that the temperature sensor 18 is exposed to ambient air during vehicle operation. As discussed in more detail below, temperature sensor 18 may comprise a thermal mass to prevent abrupt changes in the sensed temperature. Temperature sensor 18 is operably connected to module 17 by wires 20. Different control arrangements and wiring harnesses are discussed in more detail below.

Referring again to FIG. 2, heating element 2 includes first and second end portions 7 a and 7 b, respectively, each having a length “W.” In general, if the overall length A of heating element 2 and blade 1 is 18 inches, B is preferably about 7.0 inches. If A is 21 inches, B is preferably about 8.5 inches. If A is 23 inches, B is preferably about 9.5 inches, and if A is 27 inches, B is preferably about 11.5 inches. Heating element 2 also includes a central portion 8 having a length “C,” and first and second intermediate portions 9 a and 9 b, respectively, each having a length “B.”

In the example illustrated in FIG. 2, the heating element 2 comprises a film 31 having a conductive element 30 disposed on the film 31. Connectors 25 may be disposed at the ends of leads 5 to provide for connecting and disconnecting leads 5 from wires 22 (see also FIG. 3) that operably connect the heating element 2 to battery 16 of the vehicle. Alternatively, wiring 22 may be permanently connected to leads 5, and a suitable releasable connector (not shown) may be provided at module 17. The conductor 30 may comprise etched foil fabricated of nichrome or other suitable conductive material. Preferably, conductor 30 is a PTC material and comprises nickel 200 or other material having an electrical resistance that is greater at higher temperatures, and lower at lower temperatures. Use of a PTC conductor 30 provides for reduced heat production by the heating element 30 at higher ambient temperatures to thereby prevent overheating and damage to the blade assembly that could otherwise occur. Although the resistance of conductor 30 may vary depending upon the needs of a particular application, testing of a heated wiper blade 1 including a nickel 200 conductor 30 shows that conductor 30 may be configured to provide 1.74 amps at 0° F. and 1.4 amps at 40° F. Thus, the use of a PTC material provides more amps (greater heat energy) at lower temperatures and fewer amps (lower heat energy) at higher temperatures, even without a separate controller 17 and temperature sensor 18 input.

The film 31 may comprise a Kapton style ribbon/tape, a PET film, a heavy film, or other suitable film material. Furthermore, heating element 2 may comprise a silicone rubber sheet 31 having a conductor 30 disposed on the outside of the sheet 31, or the conductor 30 may be embedded in the silicone rubber sheet 31. It will be understood that the conductor 30 of FIG. 2 would appear in dashed lines if conductor 30 were imbedded in a silicone rubber sheet 31.

Still further, conductor 30 may comprise a wire heating element made of nichrome or nickel 200 or other suitable materials having an insulating cover or sheath comprising Teflon, PVC, or other suitable material. In general, Teflon is preferred due to its higher temperature capabilities. An example of a wire having a conductor 30 with an insulating outer cover or sheath is shown in FIG. 5 a of U.S. Pat. No. 7,721,382

Conductor 30 may define a series of longitudinally extending portions 32 and transversely extending portions 33. The longitudinally extending portions 32 may have a reduced length at end portions 7 a and 7 b corresponding to the dimension “W,” and also along the central portion 8 having a dimension “C.” This provides a higher heat output in the regions 7 a and 7 b and c, relative to the intermediate portions 9 a and 9 b. The conductor 30 may provide a heat output that can be expressed in terms of heat energy per unit length of heating element 2. The closer spacing of transverse portions 33 of conductor 30 provides for substantially increased heat output per unit length at the end portions 7 a and 7 b, and also at the central portion C of heating element 2. Because the conductor 30 may not extend all the way to the opposite ends of beam 14, the additional heat provided in end portions 7 a and 7 b compensates for this and reduces build up of snow and ice at the opposite ends 4 of the wiper blade. Similarly, the increased heat provided by the closer spacing of longitudinal portions 32 of conductor 30 at the central portion C compensates for additional heat loss that may occur due to positioning of conductor 30 away from beam 14 at bracket 13. It will be understood that heating element 2 may provide increased heat output per unit length at only the center portion C, or at one or both of the end portions 7 a and 7 b, or at both the central portion C and the opposite end portions 7 a and 7 b.

With further reference to FIG. 2A, heating element 2 may comprise an elongated wire 35 that is disposed directly on an upper surface 36 of beam 14. Suitable retainers, adhesives, or clips 37 may be utilized to secure the wire 35 to the beam 14. The wire 35 of heating element 2 may comprise an elongated wire made of nickel 200, nichrome, or other suitable conductive material that is encased in a sheath of insulating material such as PVC or Teflon. In general, wire 35 has an electrical resistance in the range of about 1-16 ohms per meter, depending upon the total length “A” of the beam 14, and the other requirements for a particular application.

With further reference to FIG. 2B, heating element 2 may also comprise wires 40 that are secured to upper surface 36 of beam 14 utilizing clips 37, adhesive, or the like in a manner that is substantially similar to the arrangement discussed above in connection with FIG. 2A. Wire 40 may comprise an inner conductor made of nickel 200, nichrome, or other suitable material that is covered by an insulating material such as Teflon, PVC, or the like. In general, wire 40 may be substantially the same as wire 35 discussed above in connection with FIG. 2A. Wire 40 may include portions 41 a, 41 b, and 42 providing increased heat output per unit length of the blade at opposite end portions 7 a, 7 b, and at central portion 8. Portions 41 a, 41 b, and 42 may comprise a sine wave or the like providing increased heat per unit length at the opposite ends and central portions of the heating element 2 of FIG. 2B.

With reference to FIG. 2C, a heating element 2 c corresponding to another aspect of the present invention includes a wire 45 that is secured directly to upper surface 36 of beam 14 utilizing clips 37 or other suitable connectors such as adhesives, or the like. Wire 45 may be substantially the same as wires 35 and 40 discussed above in connection with FIGS. 2A and 2B, respectively. Wire 45 may form one or more additional loops 46 providing additional heat output at end portions 7 a and 7 b, and one or more additional loops 47 at central portion 8. It will be understood that a single loop 47 may be utilized with a U-bend end 38 (FIG. 2A), or wavy portions 41 a and 41 b (FIG. 2B). Similarly, the additional loops 46 (FIG. 2C) may be utilized in conjunction with a wire having a straight central portion (FIG. 2A), or a wavy central portion 42 (FIG. 2B). Also, any combination of the features shown in FIGS. 2, 2A, 2B, and 2C may be utilized to provide additional heat at only the opposite ends 7 a and 7 b, only the central portion 8, or at the end portions 7 a and 7 b and central portion 8.

With further reference to FIGS. 4 and 5, heated wiper blade 1 may comprise a beam-type wiper blade having beam 14 and squeegee 15 that is connected to beam 14. Beam 14 may include tabs 27 (see also FIG. 8) that extend around opposite edges 29 a of squeegee 15 to thereby secure beam 14 to squeegee 15. Other suitable connecting arrangements may also be utilized. Heated wiper assembly 1 also includes elongated covers 50 a and 50 b, a central cover 51, and a bracket 13 that is utilized to interconnect the heat wiper blade 1 with an existing arm 10 of a vehicle wiper system. The beam 14, squeegee 15, covers 50 a, 50 b, and 51, as well as bracket 13 may be substantially similar to commercially available beam type wiper blades. The covers 50 a, 50 b, and 51, as well as squeegee 15 are preferably made of materials that can withstand 200-300° F. Similarly, adhesives, sealants, filler material, and the like also preferably comprise materials that can withstand temperatures of 200-300° F. In general, beam-type blades made by various manufacturers are readily available from various retail outlets. The covers, beam, and squeegee will therefore not be described in detail herein, except as necessary to describe the differences between the heated wiper blade 1 of the present application and commercially available non-heated beam type wiper blades.

Wiper assembly 1 (FIGS. 4 and 5) further includes heating element 2 which may be in direct contact with upper surface 36 of beam 14 as described above in connection with FIGS. 2, 2A, 2B, and 2C. Heating element 2 may comprise any one of the heating elements described in more detail above in connection with FIGS. 2, 2A, 2B, or 2C. As discussed above, heating element 2 may be connected to a module 17 utilizing wiring 22. It will be understood that some of the components of the wiring harness are not shown in FIGS. 4 and 5. When assembled, inner ends 52 a and 52 b of covers 50 a and 50 b, respectively, are received in openings 53 a and 53 b of cover 51. Wiring 22 may pass through opening 53 a or opening 53 b, and a heat resistant sealant 54 (FIG. 5) may be provided at openings 53 a and 53 b to provide an airtight seal between covers 50 a, 50 b, and cover 51. The heat resistant sealant 54 is also utilized to provide an airtight seal around wires 22 where they enter opening 53 a or 53 b.

With further reference to FIG. 6, a cavity 55 (see also FIG. 7) is formed by covers 50 a and 50 b. Heating element 2 is disposed in cavity 55. Sealant 54 is utilized at edges 56 of cover 50 b to provide an airtight connection between cover 50 b, squeegee 15, and/or beam 14 such that cavity 55 is substantially airtight. Edge portions 56 of covers 50 a and 50 b preferably include a tapered wedge-like surface 49 and a pair of inwardly-facing longitudinal grooves 48 (see also FIG. 8). During assembly, beam 14 is pushed into engagement with covers 50 a and 50 b such that opposite edges 24 of beam 14 engage tapered edges 49, and then snap into inwardly-facing grooves 48 (See also FIG. 8). A sealant 54 or the like is preferably disposed around the opposite side edges of heating element 2 and/or beam 14 and/or squeegee 15 to provide an airtight seal as discussed below, sealant 52 may be disposed inside covers 50 a, 50 b, and 51 (FIGS. 4 and 5). Covers 50 a and 50 b, beam 14, squeegee 15, heating element 2, and sealant 54 are preferably made of materials that are selected to withstand 200-300° F. Sealant 54 is preferably a high temperature sealant that does not degrade at the higher temperatures generated by heating element 2. The squeegee 15 is adhesively adhered, or otherwise mechanically connected, directly to beam 14, whereby upper surface 26 of squeegee 15 is in direct contact with lower surface 34 of beam 14 to thereby facilitate heat transfer there between. This also facilitates faster, more efficient assembly.

Cavity 55 may comprise an empty cavity as shown in FIG. 7, or sealant 52 or a filler material 57 (FIG. 6) may be injected into cavity 55. Filler material 57 may comprise a flexible sealant material that is capable of withstanding the higher temperatures resulting from heating element 2. In general, filler material 57 may be injected into cavity 55 in a liquid or highly viscous form, and the filler material 57 then cures to form a solid mass. Alternatively, covers 50 a and 50 b may comprise a relatively hard outer layer and filler material 57 that defines an inner core formed at the time the covers 50 a and 50 b are fabricated. The covers 50 a and 50 b and core 57 may be formed utilizing a molding process or the like. The filler material 57 is significantly softer than the outer layer of the covers 50 a and 50 b. During assembly, the covers 50 a and 50 b (with filler material 57) are snapped onto the beam as described above. The filler material 57 pushes down on the heating element 2 and causes the heating element to contact upper surface 36 of beam 14, thereby ensuring that heat from heating element 2 is transferred into beam 14. Filler material 57 also insulates the upper side of the wiper blade to prevent heat loss. The outer shell and the core filler material 57 may comprise rubber having significantly different hardnesses, or the outer shell and the core may comprise entirely different materials. For example, the covers 50 a and 50 b can comprise a relatively hard plastic, and the core 57 can comprise an elastomeric rubber. Also the outer surface of the covers 50 a and 50 b is preferably very smooth to prevent excessive buildup of snow and ice on the outside of wiper blades. Filler material 57 provides insulating properties such that more of the heat from heating element 2 is transferred to the beam 14 and to squeegee 15.

With reference to FIG. 9, bracket 13 may have a generally U-shaped cross section with a lower flange or sidewall 59 and upwardly extending flanges 58 a and 58 b. Lower flange 59 may be spaced apart from the upper surface 36 of beam 14 to form a gap 63. However, the gap 63 may be too small to allow heating element 2 to be positioned therein between lower flange 59 and beam 14. Thus, heating element 2 may be disposed in direct contact with the upper surface 43 of lower flange 59 of bracket 13. Gap 63 may be filled with filler material 57 to thereby provide increased heat transfer from flange 59 to squeegee 15 adjacent bracket 13.

With further reference to FIG. 10, heating element 2 may be disposed between lower flange or wall 61 of bracket 13 a and beam 14 if a modified bracket 13 a (see also FIG. 11) permit this configuration.

Bracket 13 a comprises a pair of generally upright side flanges 58 and 58 b that are interconnected by an internal web or sidewall 61 or the like to form a gap 62 that is large enough to receive heating element 2. Modified bracket 13 a permits heating element 2 to be disposed in direct contact with upper surface 36 of beam 14 where beam 14 extends through or adjacent bracket 13 to thereby facilitate heat transfer from heating element 2 to beam 14 or 14 a and to squeegee 15 (see also FIG. 11).

With further reference to FIGS. 11 and 12, the beam may comprise a beam 14 a having a substantially flat central portion 64 and curved outer portions 65 a and 65 b. In general, conventional beams 14 as shown in FIG. 4 have a uniform radius of curvature. This can tend to cause a gap between squeegee 15 and the windshield when the squeegee 13 is sliding over a portion of the windshield having less curvature. The straight or flat central portion 64 of beam 14 a ensures that the central portion of squeegee 15 stays in contact with the windshield surface. Also, straight or flat portion 64 reduces flexing of beam 14 a in operation, thereby reducing the tendency for heating element 2 to flex and break if heating element 2 is made from a material that cannot withstand repeated flexing. In general, the overall nominal length “A” of heating element 2 may be 18 inches, 21 inches, 23 inches, or 27 inches. The beam 14 is typically about 1 inch longer than heating element 2. The dimension “D” of flat central portion 64 of beam 14 a is preferably about 3-10 inches (depending in part, on the dimension “A,” and curvature of the windshield). In a preferred embodiment, the dimension “D” is about 4.5 inches. However, it will be apparent that the precise dimension of flat central portion 64 is not necessarily critical in all applications.

Beams 14 and 14 a may be formed from flat strips of metal by stamping or other such suitable process. In general, the curved outer portions 65 a and 65 b of beam 14 a have a radius of curvature that is similar to beam 14 (see also FIG. 4). The flat central portion 64 can be created from flat metal stock by curving only end portions 65 a and 65 b during the stamping or other forming process.

Beams 14 and 14 a may be made from spring steel or other suitable metal. Alternatively, beams 14 and 14 a may be formed from graphite, fiber glass, or a suitable polymer material. Furthermore, as noted above in connection with FIG. 1, the beams 14 and 14 a may be made from a conductive material such that the beam 14 or 14 a itself acts as a heating element as described above in connection with FIG. 1. If the beam 14 or 14 a is used as a heating element, a separate heating element 2 is not required. Referring again to FIG. 4, other components of wiper blade assembly 1, such as the covers 50 a, 50 b, 51, and bracket 13 may also be made of a conductive material and are operably interconnected with an electrical power source, whereby these components also provide a heating function. In general, these components may be made of a metal conductive material or they may comprise a conductive plastic material. Conductive plastic material may comprise a plastic resin that has been embedded with carbon powder or fiber to reduce the electrical resistivity of the plastic material. Plastic that has been formulated with stainless steel fiber, inherently dissipative polymer, or other such materials may also be utilized.

Beams 14 and 14 a may comprise an extruded polymer material, and conductor 30 may comprise an etched foil heating tape that is imbedded or extruded into the beam 14 or 14 a. Conductors 30 may be extruded into the beam 14 or 14 a. The spring beam may also comprise a carbon fiber material with conductor 30 extruded therein. The conductor 30 may comprise a nickel 200 material, nichrome, or other PTC resistance material. Leads 5 interconnect conductors 30 with the other wiring in the system. Leads 5 may protrude transversely from flat center portion 64, or from opposite ends 4 a of beam 14 a.

Heated wiper blade 1 may comprise a beam-type wiper having a pair of spring steel spines that connect to an elongated blade as shown in U.S. Pat. No. 7,721,382. The beam 14 may comprise a slotted elastic member as disclosed in U.S. Patent Publication No. 2006/0026786, the entire contents of which are hereby incorporated by reference. If the squeegee has an upper surface that is above the upper surface of the beam or beams (i.e., the beams are received in slots on opposite sides of the squeegee), the heating element may be secured directly to the upper surface of the squeegee utilizing adhesive, adhesive sealant, or the like to ensure that heat from element 2 is transferred into the squeegee.

With further reference to FIG. 13, temperature sensor 18 may comprise a block 66 that is made of aluminum or other material having significant thermal energy storage capabilities. A hole or bore 67 is formed in block 66, and a sensor element 68 is positioned in the bore 67 with wires 20 extending out of bore 67. Sealant 69 may be disposed in bore 67 to provide a watertight seal around wires 20 and to retain sensor element 68 in bore 67. If bore 67 extends all the way through block 66 to form an open end 70, the open end 70 may also be filled with sealant 69. Block 66 has a length X, a height Y, and a width Z. In general, the dimensions X, Y, and Z are chosen to insure that block 66 has sufficient thermal mass to prevent rapid temperature fluctuations of sensor element 68. If the block 66 is made of aluminum, the length X may be about 1.5 inches, and the height and width may be about 1 inch. Block 66 may be various shapes, including cylindrical or other suitable shapes.

With reference to FIG. 14, a wiring harness 75 includes a battery 16, a module 17, a temperature sensor 18 and connectors 25 a that releasably interconnect wiring 22 with leads 5 of heating elements 2 of heated wiper blades 1. The electrical connectors 25 a may be positioned adjacent an end of arm 10 (see also FIG. 3). If the heated wiper blade assemblies 1 are retrofitted to a vehicle, the module 17, the temperature sensor 18, and wiring 19, 22, and 23 may be installed in a vehicle, and connectors 25 a may be utilized to releasably interconnect harness 75 with heated wipers 1. If one of the heated wipers 1 requires replacement, it can be quickly and easily disconnected and replaced by disconnecting a connector 25 a from the wiper blade being replaced, followed by interconnecting of connectors 25 a to the replacement blade 1. In this way, once a vehicle has been retrofitted with the wiper system, only the blade portion of the system needs to be replaced in the event one of the heated blades 1 does not function properly. Alternately, a single connector 25 b and wire 22 b may be utilized to interconnect wiring 22 with module 17. Connectors 25 a and/or 25 b are preferably waterproof, 7 amp rated connectors having a very small external size to reduce the visual effects of connector 25 a. Furthermore, if connector 25 b is very small, a hole in seal 76 (FIG. 3) can be formed, and connector 25 b can be passed through the hole. If required, sealant can be applied around the hole through seal 76. This reduces disruption of the seal around the vehicle hood.

A wiring harness 85, similar to the wiring harness 75 of FIG. 14, further includes a connector 81 that may be utilized to interconnect the wiring harness to a vehicle fuse box. Alternatively, a fuse 79 and fuse clip 80 may be utilized. The portions of wiring harnesses 75 and 85 that are subject to flexing during use (i.e., the portions directly adjacent arms 10) are preferably made of a flexible wire that retains its flexibility to at least −40° F. and more preferably retains its flexibility to −76° F.

All of the connectors, wire splices, butt splices, and other components of the wiring harness are preferably moisture and waterproof. Furthermore, all of the wire and connectors preferably meet automotive specification such as TXL wire for portions of the wire that are disposed in the engine compartment and below the hood of the vehicle. The wires to the wiper blades 1 are preferably about 0.125 inches in diameter, and not less than 40 inches long, flexible, remaining flexible to −65° F. As discussed above, the wires can be connected at the wiper blades 1, or under the hood of a vehicle. If the connectors are located under the hood, there is less chance of damage to the connectors from car washes, wind, or the like. Also, as discussed above, the wire running to the wiper blades 1 must be replaced with the wipers if an under-hood connection is utilized. Thus, providing a connector at the wiper generally provides for a lower cost wiper blade, and facilitates replacement in general. The system is configured to provide power to the heated wiper blades 1 only if the vehicle ignition switch is on. Further-more, with the electrical system grounded on the wiper arms 10, only a positive lead wire needs to be run under the hood of a vehicle.

Module 17 may be configured to control the amount of electrical current supplied to heating elements 2 based on an ambient temperature sensed by temperature sensor 18. Module 17 is configured, in part, to account for the material utilized to make the heating element 2. With reference to FIG. 16, module 17 may comprise sensors 18 a and 18 b. First sensor 18A closes at approximately 0° F., while sensor 18B closes at approximately 40° F. The 40° F. sensor 18B has a dropping resister 100 that reduces the voltage to approximately 10.6 volts, from the 13.6 volts provided by a motor vehicle alternator during operation. Thus, the circuit causes less voltage and heat at the blade when the temperature exceeds 0° F. Although the 10.6 volt provides good operation in the temperature range of 0° F. to 40° F., additional heat is required when the operating conditions are below about 0° F. When the ambient temperature is 0° F. or lower, the second sensor 18B bypasses the dropping resister 100, whereby the heating element 2 of the wiper receives 13.6 volts. When 13.6 volts is supplied to the heating element 2, the wiper blade assembly 1 can be operated at temperatures between about −40° F. and 0° F., while preventing excessive heat (and attending damage) at operating temperatures from about 0° F. to about 40° F.

The module 17 thus acts as a voltage regulator. For example, module 17 may be configured to provide 8 to 10 volts to the heating element 2 when the ambient temperature reaches 40° F. As temperatures drop below 40° F., the module 17 is configured to regulate the voltage up to 13.6 volts.

Module 17 may alternatively comprise a Pulse Width Modulator (PWM) that is supplied with the vehicle at the time it is manufactured, or retrofitted to a vehicle. PWM may also comprise an aftermarket unit that is retrofitted to a vehicle and may be used with or without PTC sensor/heating element, or other sensing means. Furthermore, a motor vehicle may include a temperature sensor at the time it is manufactured. If the on-board motor vehicle includes an original equipment manufacturer (OEM) PWM and temperature sensor, module 17 can be configured to control voltage to heating element 2 to account for ambient operating conditions. For example, the PWM may be configured to provide electrical current to heating element 2 when the ambient temperature is 40° F. or lower, and the electrical current may be supplied to the heating element 2 until a temperature inside the blade as sensed by a temperature sensor exceeds about 150° F., at which point the PWM provides reduced current to prevent overheating of the heating element 2 and other components. As the temperature of the blade drops, it is contemplated that the PWM may provide less current (fewer pulses) until the temperature stays at approximately 150° F. even if the ambient temperature is −40° F.

Another aspect of the present disclosure that is particularly useful is that it provides a fully self-regulating heating element 2 for the wiper blade 1. FIG. 17 depicts such a system for a fully self-regulating heating element 2 for the wiper blade 1, especially in the case of after-market installations. It has been found that a PTC conductor 30 having a variable resistance can be employed, such that at an ambient temperature of 40° F. and below and system voltage of 12 to 16 volts, the blades do not exceed a predetermined maximum temperature, preferably 150° F. In operation, with the voltage only delivered at temperatures below 40° F., the temperatures at which icing and freezing of the wiper blade 1 can occur, the PTC material causes the electrical resistance of the conductor 30 to lower in accordance with lower ambient temperatures, thereby providing increased heat from the conductor 30 such that the exterior surfaces of the wiper blades 1 tends to stay at approximately the same temperature, without control by a separate controller and temperature sensor.

The specific resistance level of the conductor 30 will generally depend on the configuration of the various components, such as the beam 14 and covers 50 a and 50 b, as well as the presence or absence of filler material 57 (see, e.g., FIG. 6). Thus, no two systems are the same and the proper resistance level for the heating element 2 must be determined by testing different conductors 30, until the proper resistance level (resistance per unit length) provides an appropriate temperature range experienced at the exterior of the blade (preferably between approximately 125° F. to 150° F. when the ambient temperature is 0° F. to 40° F.) and not to exceed 150° F. At more extreme cold temperatures (e.g., between −40° F. and 0° F.), obviously the exterior blade temperature may fall below 125° F. As discussed above, in general, conductor 30 will have a resistance in the range of approximately 1-16 ohms per meter, if conductor 30 comprises a wire having a conductive element made from PTC material such as nickel 200 or other conductive material and an insulating sheath made of Teflon, PVC, or the like.

For the automatic, self-regulated heated wiper system, the manual switch 21 and wire 23 can optionally be omitted. Rather, as shown in FIG. 17, the temperature sensor 18 is preferably combined with module 17 and situated just below the windshield to allow power to the wiper blades 1 only when the temperature sensor 18 detects an ambient temperature of less than 40° F. That is, module 17 in combination with temperature sensor 18 acts as a simple on/off switch. Once the temperature drops below 40° F. and the power is switched on, the current flow though the heating element 2 is self-regulating. The module 17 of the self-regulating system also saves space, as it requires a volume of only 1.25 inch by 1.5 inch by 0.5 inch.

The temperature sensor 18 may be located between the hood 11 (when closed) and the bottom of the windshield 12. Alternatively, the temperature sensor 18 can be attached to the windshield 12. Thus, a single temperature sensor 18 can be employed for both wiper blades 1. Moreover, the wiring harness 22 for the system can be simplified to two connectors 25, one for each wiper blade 1, and a connector 25 b that goes to the wiring harness of the module 17.

Alternatively, the temperature sensor 18 can be spliced into the wire 22 extending between the wiper blade 1 and the hood 11. That is, the temperature sensor 18 may be incorporated into the wiring 22 to the wiper blade 1 (see, i.e., FIG. 18). Preferably, each wiper arm 10 houses a temperature sensor 18, as shown in FIG. 19, which can be molded, covered, or otherwise provided with a thermal mass for thermal energy storage to prevent rapid temperature changes, thereby creating an inaccurate temperature signal, as discussed above. In the case of new motor vehicles, the temperature sensor 18 may already exist and the present system can be wired into the motor vehicle's existing system. However, there are disadvantages with wiring the wiper through the vehicle electrical system, in that voltage drops may occur from using the electricity from the vehicle's electrical system.

Rather, a benefit of the disclosed self-regulating system is that it can be wired directly to the battery. Thus, the voltage delivered to the heating elements 2 is maximized and voltage drops that may occur from using the electricity from the vehicle's electrical system are eliminated. It has also been found that when using an OEM remote starter, some motor vehicles use a wiring platform will not energize the circuit when the vehicle is started. Moreover, some circuits shut off in certain conditions when the vehicle is running. Connecting the self-regulating system directly to the battery avoids these shortcomings.

Preferably, the self-regulating system is provided with self diagnostic LED light 95 on the module 17 that illuminates when voltage is supplied to the wiper blade 1. The self-regulating system also is preferably provided with an electronic fuse 96 (such as that manufactured by Polyfuse) that protects the system from shorts or overloads. When the short circuit is resolved, such fuses automatically reset. Thus, the use of electronic fuses avoids the need to replace traditional fusible links.

Due to the simplicity of the self-regulating system, there are only three wires required, as shown in FIG. 20. The first wire 19 is connected to the positive post 93 on the battery 16. The second wire 19 a is connected to the negative post 91 of the battery or ground, or, in the case of grounding to the wiper blade 10, to the wiper blade 10. The third wire 22 is connected to the heating elements 2 of the wiper blade as discussed above. A power switch 97 is controlled by the temperature sensor 18 and closes the circuit to allow power to the heating element 2 at temperatures below 40° F. A voltage comparator 98 and voltage reference 99 are connected with power switch 97 in the circuit. As noted above, most motor vehicle battery and charging systems deliver 14.6 volts after the motor vehicle has been started and approximately 12.6 volts when the motor vehicle is not running. Thus, the voltage comparator 98 compares the voltage in line 19 to the reference voltage 99, and actuates power switch 97 when the voltage drops below a predetermined level, such as preferably 13.0 volts, so that power is cut off to the self-regulating system when the motor vehicle is not operating. Optionally, although not required, a manual switch 21 can be added to the circuit.

Several advantages can be realized through the aforementioned self-regulating system. First, as noted above, at colder ambient temperatures, the amperage drawn by the heating element increases to increase the heat output of the heating element 2 and to thereby maintain the external temperature within an acceptable temperature, preferably not to exceed 150° F. Also, the self-regulating system disclosed herein has been found to heat up approximately twice as fast as heated blades without PTC materials. Further, as the motor vehicle moves faster in colder weather, the air flow over the wiper blades 1 tends to cool the heated wiper blades 1. As this happens, the PTC material will draw more amperage, causing the wiper to increase heat output and re-warm the blade 1. As the wiper blade 1 reaches the desired temperature, the PTC material will draw less amperage, preventing the wiper 1 from getting too hot. Finally, the self-regulating system disclosed herein allows the system to be easily wired without the use of the motor vehicle electrical platform or system. It requires just a positive lead 19 to the wiper 1, relying on the negative ground 19 a of the wiper to complete the circuit to the battery 16.

As an aspect of the present disclosure, it has been found that the use of PTC material is advantageous (in tape and wire form) for the small space of the wiper blade 1 to obtain self-regulation. It has also been found that winding or thickening the PTC material improves self-regulation. Providing a maximum heating surface area or material gives a wider range of amperage between hotter and colder ambient temperature operation. For instance, with smaller heating surfaces of the heating element 2, the amperage differential between hotter and colder ambient temperature operation is only a few tenths of an amp. By maximizing the heating surface of the heating element 2, approximately a 1.1 amp differential between hotter and colder ambient temperature operation can be obtained for a 16-inch blade. That is, a 16-inch blade having a heating element 2 constructed from PTC materials and with an increased heating surface area draws 1.3 amps or higher when fully heated. When cold, the same 16-inch blade draws 2.4 amps or more depending on the temperature, resulting in a 1.1 amp differential. In the case of a 28-inch blade, a differential of approximately 1.6 amps can be obtained. That is, a 28-inch blade with a heating element 2 constructed from PTC material and having a maximized surface area when fully heated draws about 1.76 amps. When cold, it will draw 3.36 amps or more depending on the temperature. Colder temperatures result bigger differentials. This, of course, would vary depending on how heavy or light the blades are manufactured. The ability to draw greater amperages at lower temperature significantly improves the performance of the heated wiper blade 1, decreases the time necessary for it to heat up, and causes the external temperature of the heated wiper blade 1 to be automatically maintained between an acceptable temperature range, preferably not to exceed 150° F.

It has also been learned that not only the amount of PTC material and the surface area of the heating element make a difference, but also that the thickness of the coating, whether made of PVC, tefzel, cambridge, kapton, butyl rubber, etc., is a factor. If the material is too thick, the PTC material warms up to the desired temperature, but outputs less heat. If the coating is thinner or of a type that releases heat faster, greater differentials in the amperage change can be realized.

The PTC material can be in either wire or tape form and can be straight, coiled, sinuous, etc., as noted above. Preferably, the heating element 2 made of the aforementioned PTC material is made of a wire winding of nickel 200 having a thickness of 0.080 inch and having 24 to 34 windings per inch.

Thus, self-regulating heated wiper blades can be obtained and requires the balance of several factors: the area of the heating surface; the PTC material (nickel 200 works best, but stainless steel, silver, nichrome, nickel, nickel in combination with copper, iron, kanthal, PTC ceramic, and or lean nickel also are useful); the thickness and type of coating material (such as whether the heating tape or wire is touching or glued to the metal beam, cover, and squeegee and whether an air space is provided); the blade size (the size and mass of the blade used) and the amount of material or the type of blade (nearly every blade length requires a different resistance per foot of heating elements and whether the material is straight with a relatively large surface area, sinuous on a tape, or wound wire with as many windings as possible); and the voltage supplied to the system (typically 12.5 volts to 16 volts, where the higher the voltage, the bigger the differential or sensitivity to temperature).

An important consideration is that for each length, size, or mass, the amount of resistance per foot must be balanced. There should be as much heating surface area of the heating elements as possible. The coating of the heating element should be thin enough so the heating element does not simply warm up and slow the rate at which the current is being drawn, but not so thin that the wire or tape becomes too hot on the surface and burns the material of the blade. The self-regulating system disclosed therein essentially becomes a voltage regulator (without the additional expense and weight) and thus ensures that the heating element 2 is provided with the maximum amount of voltage from the battery of the vehicle.

In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise. 

The invention claimed is:
 1. A heated wiper blade assembly for vehicle windshields, comprising: at least one elongated curved beam comprising a flexible material suitable for conforming to a curved windshield, the curved beam defining oppositely facing upper and lower sides; a bracket connected to the central portion of the elongated curved beam, wherein the bracket is configured to releasably connect the heated wiper blade assembly to an arm of vehicle windshield wiper system; an electrical resistance heater comprising an elongated electrical conductor that produces heat when electrical current is passed through, the electrical conductor having an electrical resistance that varies with the temperature of the electrical conductor whereby the electrical resistance heater provides more heat energy at a first lower ambient temperature than at a second higher ambient temperature, and wherein the electrical resistance heater is disposed along the elongated curved beam adjacent the upper surface thereof; and a cover extending over portions of the electrical resistance heater to thereby prevent direct exposure of the electrical resistance heater to air moving adjacent a vehicle in use.
 2. The heated wiper blade assembly of claim 1, wherein the motor vehicle includes a battery having a positive battery voltage and the heated wiper blade assembly includes a control module connected to the electrical conductor, and wherein the module is connected directly to the positive battery voltage.
 3. The heated wiper blade assembly of claim 1, wherein the module actuates the electrical resistance heater in response to operation of the motor vehicle.
 4. The heated wiper blade assembly of claim 1, wherein the material for the electrical conductor is selected from the group consisting essentially of nickel and its alloys, stainless steel, silver, copper, iron, kanthal, and PTC ceramic.
 5. The heated wiper blade assembly of claim 1, wherein the material for the electrical conductor comprises nickel
 200. 6. The heated wiper blade assembly of claim 1, further comprising a temperature sensor for selectively providing power to the electrical conductor only when the ambient temperature falls below a predetermined temperature.
 7. The heated wiper blade assembly of claim 6, wherein the predetermined temperature is 40° F.
 8. The heated wiper blade assembly of claim 6, wherein the exterior temperature of the heated wiper blade is maintained below 150° F. at ambient temperatures of 40° F. or below when power is provided to the electrical conductor.
 9. The heated wiper blade assembly of claim 6, wherein the electrical conductor is provided electrical power through a flexible lead wire and the temperature sensor is incorporated into the flexible lead wire.
 10. The heated wiper blade assembly of claim 6, wherein the temperature sensor is attached to the arm of the vehicle windshield wiper system.
 11. The heated wiper blade assembly of claim 2, wherein the motor vehicle further comprises an engine compartment having a closable hood and wherein the module is mounted in the engine compartment below the hood.
 12. The heated wiper blade assembly of claim 5, wherein the temperature sensor is mounted on the curved windshield.
 13. The heated wiper blade assembly of claim 1, wherein the electrical resistance heater is provided in a circuit having an LED actuated by current flow.
 14. The heated wiper blade assembly of claim 1, wherein an amperage differential drawn by the electrical conductor between the first lower ambient temperature and the second higher ambient temperature exceeds more than 1 amp.
 15. The heated wiper blade assembly of claim 1, wherein: the electrical conductor comprises a wound wire having a thickness of less than 0.080 inch.
 16. The heated wiper blade assembly of claim 15, wherein the wound wire is comprises 24 to 34 windings per inch.
 17. The heated wiper blade assembly of claim 1, wherein the electrical resistance heater comprises a thin flexible film, and the electrical conductor comprises a foil disposed on a side face of the film.
 18. A heated wiper blade assembly for vehicle windshields, comprising: at least one elongated curved beam comprising a flexible spring material suitable for conforming to a curved windshield and returning to an original shape, the curved beam defining oppositely facing upper and lower sides, a central portion, and first and second opposite ends, and wherein the elongated curved beam comprises a conductive material; a first electrical conductor connected to the first end of the beam and a second electrical conductor connected to the second end of the beam, whereby the beam generates heat when electrical power is supplied to the first and second electrical conductors, both the first and second electrical conductors having an electrical resistance that varies the amperage drawn by the electrical resistance heater between hot and cold ambient temperature operation by more than 1 amp with changes between a first and second ambient temperature, whereby the electrical resistance heater radiates more heat energy at lower temperatures; an elongated flexible squeegee attached to the elongated beam; and wherein the squeegee is made of a material having significantly less stiffness than a stiffness of the flexible spring material of the beam, and wherein the beam is sufficiently stiff so as to cause the squeegee to curve and conform to a shape of the beam; a bracket connected to the central portion of the elongated curved beam, wherein the bracket is configured to releasably connect the heated wiper blade assembly to an arm of vehicle windshield wiper system; and a cover extending over portions of the beam to thereby prevent direct exposure of the beam to air moving adjacent a vehicle in use.
 19. The wiper blade assembly of claim 18, wherein the heating element is configured to generate increased heat energy adjacent opposite ends of the beam relative to intermediate portions of the beam that extend between the central portion toward opposite ends of the beam.
 20. A method of heating a wiper blade assembly for vehicles, the method comprising the steps of: providing an elongated flexible beam defining upper and lower sides; mounting a soft, flexible squeegee extending along the lower side of the flexible beam; fixing an elongated electrical heating element extending along the upper side of the beam, the heating element comprising a positive temperature coefficient material that generates a first heat energy output when the heating element is at a first temperature, and generates a second heat energy output that is significantly less than the first heat energy output when the heating element is at a second temperature, the second temperature being significantly greater than the first temperature; and mounting a cover member to the beam, wherein the cover member comprises an outer layer and an inner core, wherein the outer layer is significantly harder than the inner core, and wherein the inner core pushes the electrical heating element into contact with the upper side of the beam. 